A leading private hospital in Bangkok has admitted that one of its cancer patients was inadvertently infected with HIV during a blood transfusion.

The revelation came after the patient told the media he contracted the virus after paying 7 million baht for chemotherapy at Bumrungrad Hospital.

In a statement issued to the media, the prestigious hospital confirmed the error and offered a public apology.

“Bumrungrad International Hospital is truly sorry for what has happened to the patient,” part of the statement said. “We would like to express our deepest regrets for what has happened and our sympathy for the patient as well as the family suffering the effects of the situation.”

The hospital, which is consistently ranked among Thailand’s best and most expensive, said the blood it acquired from the Red Cross contained the virus, which could not be detected at the time of donation.

“A limitation in the blood screening for infection is the window-period risk,” the statement said. “This is the probability that the virus amount in the donor’s blood is too little to be detected during the early stage of infection, which, in turn, makes it possible for the patient recipient of the blood donated to become infected although there is very little possibility.”

It added, “As a result, hospitals all have a practice guideline where a patient is informed of the risks of possibly getting certain infections including HIV from blood transfusions and signs the consent form to get blood transfusions as necessary treatment.”

“We would like to take this opportunity to promise that we will continue doing our best to treat this patient,” the statement said. “We will also consider providing proper additional assistance related to treatment and care according to ethics of care and humanitarian principles.”

A statement by the Red Cross in 2017 said HIV can only be detected about one to two weeks after an infection.